Thank you everyone for all your advice and horror stories. It is very hard to know what to do for the best since so much of my Dad's self esteem is tied up with being a driver. I've discussed it with my stepmother (who is much younger than Dad) who is very anxious about him too. She has decided to say that she will not drive in the car with him driving since she feels too worried. He has been using her as his lookout when he has driven so I'm not sure he will drive if she won't be a passenger. I do think that there should be an online reaction time test that those over 70 have to take every three years when the licence renewal comes up. It is not fair to ask the GP to poison their relationship with the elderly patient and it is really hard for families who are concerned. A neutral test would result in the licence being cancelled and the insurance company informed so there would be no argument about it. I don't think it is reasonable to ask them to do a whole driving test but there must be some way of dealing with this problem that seems to cause concern to many families.